1. Field of the Invention
The present invention relates to a method for forming a thin film, and more particularly, to a method for forming a thin film and a method for fabricating a liquid crystal display device using the same, in which a process is simplified and uniform thin film characteristic can be obtained.
2. Discussion of the Related Art
Traditionally, an aluminum or its alloy has been used as a line material of a semiconductor device or a liquid crystal display device. Recently, there has been an increase in the use of copper having excellent electric conductivity as the line material in semiconductor device and liquid crystal display devices instead of aluminum.
A related art method for forming a copper thin film uses either a Plasma Vapor Deposition (PVD) method based on sputtering or a Chemical Vapor Deposition (CVD) method regardless of whether the semiconductor or liquid crystal display device has a glass substrate or a silicon substrate. These methods have a problem in that a wet chemical process is required, and therefore additional complicated processes, such as removing, washing, and drying, are required.
A related art method for forming a copper thin film will be described with reference to the accompanying drawings.
FIGS. 1a to 1d are sectional views illustrating a related art method for forming a copper thin film.
As shown in FIG. 1a, a barrier layer 12 is formed on a substrate 11, and a first metal layer 13, an insulating layer 14 and a dielectric layer 15 are sequentially deposited on the barrier layer 12. A silicon substrate is used for a semiconductor device or a glass substrate is used for a liquid crystal display device.
A photoresist is deposited on the dielectric layer 15 and then patterned by exposure and developing processes. Thus, a photoresist pattern 16 is formed to selectively expose a surface of the dielectric layer 15.
Subsequently, as shown in FIG. 1b, the dielectric layer 15 is selectively removed by an etching process using the photoresist pattern 16 as a mask to partially expose a surface of the insulating layer 14. Then, O2 plasma process is performed in such a manner that O2 gas is permeated into the insulating layer 14 to react with the first metal layer 13. As a result, a metal oxide 17 is formed.
Afterwards, as shown in FIG. 1c, the substrate 11 is loaded into etching equipment, and beta-diketone vapor is implanted into the substrate 11 under the ambient temperature of 100˜450° C. to remove the metal oxide 17.
Finally, after the substrate 11 is loaded into the CVD equipment, a second metal layer 19 is formed. Thus, the related art process for forming a thin film is completed.
At this time, the substrate 11 is loaded into the CVD equipment after additional processes, such as washing, rinsing, and drying, are performed. This complicates the whole process.
The first metal layer 13 and the second metal layer 19 are formed of copper which will be expected to substitute for aluminum as a line material of a semiconductor device or a liquid crystal display device.
However, the related art method for forming a thin film has several problems.
First, in case the metal, specifically copper, is formed by the CVD process, resistivity of a copper film increases and foreign substances may contaminate the copper film during the process steps. Also, surface uniformity is too poor to control following process steps.
Furthermore, although an oxide film is etched in the etching equipment, a new oxide film grows during loading from the etching equipment into deposition equipment, which is separate from the etching equipment. A number of processes such as washing, rinsing and drying are required to remove the oxide film. For this reason, the number of steps in the whole process increases. This could lead to increased processing time and production cost.